Poster presentation

Study of the g-matrix in heretoatom-substituted nanographenes
Antonio Cebreiro¹ and D. Casanova^1,2

1 Donostia International Physics Center (DIPC), 20018 Donostia, Euskadi, Spain
2 Ikerbasque Foundation for Science, 48009 Bilbao, Euskadi, Spain

Graphene nanoribbons offer an excellent playground for exploring spin states and thus promising prospects in quantum spintronics devices. Although magnetism in these molecules is usually related to the existence of delocalized magnetic edge states, by heteroatomic substitution it is possible to generate spin-polarized states around the heteroatoms [1]. The magnetic behaviour of these graphene-based systems is usually modelled by means of an effective spin Hamiltonian containing spin operators and the coupling parameters between the spin centres. Amongst them, the g-matrix parametrizes the interaction of electronic magnetic dipole moments with an external magnetic field (Zeeman effect). It can be observed in electron paramagnetic resonance spectroscopy (EPR).

In this work, we characterize the g-matrix in different boron and/or nitrogen doped graphene nanostructures where the presence of the spin states is controlled by tuning the separation between the doping units. Using a procedure developed by Tatchen et al. [2] that requires the total electronic magnetic moment on a spin-orbit coupled state basis, the g-matrix is obtained using a projection technique. Spin states and interstate couplings are obtained by means of the wave function electronic structure method “Restricted Active Space Spin-Flip” (RAS-SF) [3, 4].

[1] Phys. Rev. Lett. 125(14), 146801 (2020).
[2] J. Chem. Phys. 130(15), 154106 (2009).
[3] Phys. Chem. Chem. Phys. 11(42), 9779-9790 (2009).
[4] J. Chem. Phys. 153(21), 214107 (2020).